Solve for $x$ and $y$ using substitution. ${x+5y = -5}$ ${y = -x+7}$
Explanation: Since $y$ has already been solved for, substitute $-x+7$ for $y$ in the first equation. ${x + 5}{(-x+7)}{= -5}$ Simplify and solve for $x$ $x-5x + 35 = -5$ $-4x+35 = -5$ $-4x+35{-35} = -5{-35}$ $-4x = -40$ $\dfrac{-4x}{{-4}} = \dfrac{-40}{{-4}}$ ${x = 10}$ Now that you know ${x = 10}$ , plug it back into $\thinspace {y = -x+7}\thinspace$ to find $y$ ${y = -}{(10)}{ + 7}$ $y = -10 + 7$ $y = -3$ You can also plug ${x = 10}$ into $\thinspace {x+5y = -5}\thinspace$ and get the same answer for $y$ : ${(10)}{ + 5y = -5}$ ${y = -3}$